This invention relates to a ring binder mechanism for retaining loose-leaf pages, and in particular to an improved ring binder mechanism for opening and closing ring members.
A ring binder mechanism retains loose-leaf pages, such as hole-punched pages, in a file or notebook. It has ring members for retaining the pages. The ring members may be selectively opened to add or remove pages or closed to retain pages while allowing the pages to be moved along the ring members. The ring members mount on two adjacent hinge plates that join together about a pivot axis. An elongate housing loosely supports the hinge plates within the housing and holds the hinge plates together so they may pivot relative to the housing.
The undeformed housing is slightly narrower than the joined hinge plates when the hinge plates are in a coplanar position (180 degrees). So as the hinge plates pivot through this position, they deform the resilient housing and cause a spring force in the housing that urges the hinge plates to pivot away from the coplanar position, either opening or closing the ring members. Thus, when the ring members are closed the spring force resists hinge plate movement and clamps the ring members together. Similarly, when the ring members are open, the spring force holds them apart. A pivoting lever is often provided on one or both ends of the housing for engaging the hinge plates and moving them through the coplanar position to open and close the ring members. An example is shown in co-owned U.S. Pat. No. 5,180,247 (Yu).
In many ring mechanisms, the lever is not secure when the ring members are in the open and/or closed position. There may be “play” in the lever producing an unstable feeling in the mechanism. This “play” is often due to variances in manufacturing mechanisms so that the levers disengage the hinge plates when the ring members are in the open and/or closed positions. It would be desirable to provide a more stable ring mechanism in which the lever is in continuous engagement with the hinge plates during operation of the ring mechanism so that the lever is held against “play” when the ring members are in both the open and closed positions.